SQL IF SELECT query is null then do another query

Question

I have a query that regularly returns "nothing", and I would like to run a different query if this is the case, but I know not of the way of doing this. If anyone could be of help please.

Here is the current code I am using...

SELECT * FROM cfg_users JOIN cfg_ash ON cfg_users.iUserId = cfg_ash.iUserid WHERE iTeamId='0' AND sDisabled IS NULL AND iStatusId > 0 AND sDate = '2014-08-01' GROUP BY cfg_users.iUserId ORDER BY iStatusId, sName

I basically want to say

IF <my code> IS NULL THEN <do other code>, IF <my code> IS NOT NULL THEN return the result.

Thanks

Answer 1

There are some simple way only use sql.

Define your first query as a temp table, with union all, filter the second query with temp table's count.

with temp as (select * from t1 where 1=0)
select * from temp
union all
select * from t2 where (select count(*) from  temp) =0

This query will return the second table's records.

with temp as (select * from t1 )
select * from temp
union all
select * from t2 where (select count(*) from  temp) =0

And if temp query have result, only return temp query.

You can test with sql fiddle here.